Rheostat.



no. 665,903.. Batman Ian. l5, |9ol.

E. M. HEWLETT.

,i nHEos'rAT.

(Application Bled Nov. 13, 1900.)

(No lodgl.) 2 Sheets-Sheet l.

lll

Witnesses. I. j Jnv'entor b Edward M. Pievvletpip', y

YH: News Perma co, ro'rmwuo., msumurow. n. c.

Patented lan. I5, |90l.`

No, 665,903.Y

E. M.'HEWLETT.

' RHEosTAT.

(Applicatiqn led Nov. 13, 1900.)

A 2 Sheets-Sheet 2.

(N0 Model.)

lrwentl"l Edward MfHewlett,

Witnesses UNITED STATES l-ATEEVF OEEICE.

EDWARD M. HEWLETT, OF SCHENECTADY, NEIV YORK, ASSIGNOR T TI-IE GENERALELECTRIC COMPANY, OF NEV YORK.

RH EOSTAT..

SPECIFICATION forming part of Letters Patent No. 665,903, dated January15, 1901.

Application led November 13, 1900. Serial No. 36,362. KNO model.)

To all whom it may concern: nitely indicated in the claims appended toBe it known that I, EDWARD M. HEWLETT, a this specification. citizen ofthe United States, residing` at Schen- In the accom panying drawings,which illusectady, county of Schenectady, State of New trate myinvention, Figure l is a front eleva- 55 York, have invented certain newand useful tion ofa motor-driven rheostat employing my Improvements inRheostats, (Case No. LMA) improvements. Fig. 2 is a sectional elevationof which the following is a specification. on a plane at right angles tothat of Fig. l.

This invention relates to I )ower-controlled Fig. 3 is a diagram showingthe plan of conrheostats, the object being to permit the in struction ofthe rheostat and its relation to 6o 1o troduction or withdrawal from thecircuit to the governed and controller circuits, and Fig.

be governed of a desired variable amount of 4 is a detail View of therheostat-brush.

resistance, the resistance-switch being gov- Referring `first to Figs. land 2, the rheoerned by a source of power controlled by an stat iscomposed of a range of copper orphosoperator. phor-bronze contacts l llb, dac., solidly 65 One particular use of the invention is the mountedon a slate base and separated by an regulation of resistance in thefield-circuit of air-space or otherwise insulated one from anadynamo-electric machine for varying the other. I preferably arrangethesein the form voltage of the machine, it being desirable to of acircle, mounting` within the circle an be able to manipulate a device ofthis charannulus of conductive metalZ, between which 7o zo acter bymeans of a control-switch at a disand the several contactscross-connection tance from the rheostat. may be made by means of alaminated phos- In carrying out my invention I provide a phor-bronzebrush 3, spanned by a yoke on range of contacts electrically connectedwith the end of a cast-metal arm 4, journaled in a different resistancesections or spools of the bushing mounted in the base. Bolted to this 75rheostat, in coperative relation to which I brush-arm and insulatedtherefrom is a shaft provide a brush-contact operated by an elec- 5,carrying a worm-gear 6, inclosed within a tric motor connected with aspeed-varying cast-metal casing 7, supported by and formandcurrent-reversing controller. I provide ing a part of a spider 8, boltedto the base by also an automatic switch for opening the moarms 9 9a,dac. The worm-gear engages a 8o 3o tor-circuit independently of thecontroller as worm 10, mounted on a shaft jointed to the the limit oftravel over the range of contacts shaft of an electric motor l1 by aiiexible is approached at either end, these limitjoint, as indicated atl2. Between the sevswitches being so arranged that the motoreralcontacts la lb, thc., are interposed seccircuit will always be in propercondition to tions of a continuous resistance in the usual 85 start therheostat into action. I provide also manner, the segment l beingdisconnected means for indicating to the operator whether so as to forma dead-point upon which the the rheostat is in working order, employingbrush may rest when the circuit is open. Sefor this purposeatelltaledevice which gives cured to the brush 3 is a plate or bar 13,

a visual or other indication when the rheobridging the under side of thecontacts and 9o 4o stat-contacts are in proper engagement fora thering-contact 2 and holding the brush or stable condition of the circuit,thereby prebridging contact 3 down into iirm engageventing the rheostatbeing left in a position ment with the face of the rheostat. Thus thewhere these contacts d0 not have agood curbrush is independent of thearm 4, but may rent-carrying capacity, and thus avoiding be pushed by itin either direction, as is evi- 95 damage to the apparatus. dent fromFig. 1l. This construction permits My invention embodies also featuresof the the brush to make a good contact at all times motor-controller bywhich the movements of Whether the arm is in true parallelism to the thepower-governed rheostat are quickly arcontact or not. An auxiliaryinsulated brush l rested when the circuit is opened. or bridging contactle is mounted on bar 13 roo 5o The novel features will be moreparticuand cross-connects a ring 15(1nore clearly larly hereinafterdescribed and will be deiseen in Fig. 3) and any one of the range ofcontacts governing a telltale or indicator, as will be presently setforth. As thus organized, the rheostat and its operating-motor may bemounted near the machine to be governed or at any other suitable point,connec- -tions being led therefrom to the circuit to be governed-as, forexample, thefield-magnet of a dynamo-electric machine-and to thecontroller by which the movements of the rheostat are governed, whichlatter may be mounted on a switchboard with suitable indicatinginstruments.

1n the diagram, 17 represents the armature, and 18 the held-magnet, of agenerator the potential of which it may be desired to regulate, and A Brepresent the bus-bar or mains, with which the Generator may connect 19represents the telltale, the type shown being a visual indicator-as,'for example, an incandescent lamp-in a branch circuit from the bus-bar,the closure oi which is determined by the auxiliary brush 11, whichspans the ringcontact 15 and the contacts 16 16, ttc. Thesetelltale-contacts are arranged in an annular group and are the sameangular distance apart as the main contacts 1 1, the., ot the rheostat.They subtend, however, a smaller angle, serving thus to indicate bymeans of the lamp 19 when the brush 3 is squarely upon one of thecontacts of the rheostat. 1f the latter bears upon one edge only of oneof the contacts, the telltale-contact Will not be bridged, and the lampwill therefore not be lighted. One termin al of the circuit to begoverned-forexample, the held-magnet coil 1S-may be connected with thering-contact 2 of the rheostat and one end of the resistance with themain A, the other end of the field-coil being` connected with the mainB. At or near the limits of movement of the rheostat-brush l placelimit-switches 2O 20, being pivoted switches provided with projectionslying in the path of an insulated projection 21, mounted on the end ofthe brush-arm. These are set in a short distance from the end of travelof the brusharm, so that the momentum oi the motor after it is cut ontmay be absorbed in carrying` the brush to the open-circuit position, andwhen one limit-switch is open the other is closed and adapted to reversethe direction of operation of the rheostat. Inl the return movement ofthe brush the projection 21 strikes the pivoted switch-lever 2O or 2O1(according to the direction of movement) and recloses thelimit-switch.These limit-switches are interposed in the armature-circuit of the motorwhich drives the rheostat and in such relation, as indicated in Fig. 3,to two Wires 22 22, leading to the controller, as to give oppositedirections of movement to the armature. The controller is provided witha fixed range of contacts and a movable drum adapted to reverse themotor-circuit or cut in or out resistance to vary its speed. Thecontroller is so designed that after the armature is disconnected fromthe line it is shortcirc uited fora moment before the held-circuit isopened. ln starting 'the motor the lirst movement ofthe controller ineither direction closes the field-magnet circuit, then opens the shortcircuit for the armature, and cuts thc armature into line withresistance. The second movement cuts out the resistance, thus permittingthe motor to speed up. 'lhus in the position indicated in the diagramthe field-magnet circuit ot' the drivingA motor is open and thearmature-circuit is closed by way of conductor 23, contacts 20 20, wires22 22, controller-contacts 24- 25, bridging-contact of the controller tocontact 2G to the other brush olf the armature. By moving the controllerin either direction this short circuit is openedA and the field-magnetcircuit closed by way oi" contact-s 27 2h and 2.() SO, this circuitincluding a blow-out magnet 3l, as usual in the construction ot'controllers. The next position of the controllercloses thearmature-circuit, asindicated in the position marked 1 in the diagram,in which case thc armature-circuit is closed through the resistance 32.The final position of the controller is indicated by the dotted lines 22 in the diagram, in which the resistance has been cut out and the motoris at maximum speed. The operator recognizes by the blinking of the lamp1.() that the rheostat is in good working order and also knows when asuilicient amount of resistance is out in exactly at what point to leavethe rheostat, since if the lamp 19 is not lighted the motor must bestarted ahead a triile until the lamp burns, when the best relation ofcontact engagement between the rheostat-brush and its contacts ismaintained.

What 1 cia-im as new, and desire to secure by Letters Patent of theUnited States, is

1. A. power-driven rheostat comprising a motor, and a limit device i`orcutting out the motor, automatically operated when the rheostat-contactnears its limit of movement.

2. A motor-driven rheostat comprising an electric motor, a rhecstatcontact driven thereby, a circuit-controller `for the motor, andlimit-switches to automatically interrupt the motor-circuit near thelimit-s of travel of the contact. 3. A power-driven rheostat comprisinga motor, a movable rheostat-contact driven thereby to vary theresistance, and a limit device to cut in or out the motor as the contactpasses or returns to a definite point of its travel.

It. A motor-driven rheostat comprising a range of resistence-varyingcontacts, a contact-brush sweeping the same, an electric motor in gearwith the brush, a limit-switch in the motor-circuit, and a projectionmoving with the brush to engage said switch at a definite point of itstravel.

5. A power-driven rheostat comprising a vrange of resistance-varyingcontacts, a motor-driven brush adapted to successively engage the same,and a telltale or indicator to show when the contacts are in goodconductive relation.

IOO

IOS

IIO

6. A power-driven rheostat comprising a range of resistance-varyingcontacts, a motor-driven brush adapted to progressively engage the same,and an indicator operated when the contacts are engaged.

7. A power-driven rheostat comprising a range of resistance-varyingcontacts, a motor-driven brush adapted to progressively engage the same,and an incandescent lamp cut into circuit when the brush bears squarelyon a contact.

8. A rheostat comprising a circular range of resistancevarying contacts,a movable brush to progressively engage the contacts, an arm carryingthe brush, and a guide at the outer end of the arm to hold the brush inrm engagement with the contacts.

9. In a rheostat, a base-plate, a range of resistance-varying contactsmounted thereon, a brush-arm, a spider mounted on the baseplate, agear-wheel attached to the arm and mounted on the spider, and a motor ingear with the wheel.

10. A power-driven rheostat comprising a range of resistance-varyingcontacts, a movable brush to progressively engage the same, an electricmotor to drive the brush, and a controllei` provided with contacts toput the motor-armature on short circuit when the motor is cut out.

l1. A power-driven rheostat comprising a range oi' resistance-varyingcontacts, a movable brush to progressively engage the same, an electricmotor to drive the brush, a controller to close the armature on shortcircuit when the motor is cut out, and a limit-switch on the rheostat tocut out the motor at a deflnite point of movement of the brush.

l2. The combination with a plurality of contacts, a brush movablethereon and held in engagement therewith, and a lever or arm looselyengaging the brush but mechanically disconnected therefrom.

13. A power-driven rheostat comprising a range of resistance-varyingcontacts, a movable brush to progressively engage the same, a motor todrive the brush, a circuit-controller and limit-switch at differentpoints of the brush travel to automatically open the motor-circuit whenthe brush reaches a determinate position, said switches being connectedto effect opposite directions of movement of the armature. v

In Witness whereof I have hereunto set my hand this 12th day ofNovember, 1900.

EDWARD M. HEWLETT.

Witnesses:

BENJAMIN B. HULL, MABEL I-I. EMERSON.

